Variable pressure honing tool and method



Dec. 9, 1941. w, co ETAL 2,265,800

VARIABLE PRESSURE HONING TOOL AND METHOD Filed Nov. 18, 1938 3 Sheets-Sheet 2 Q lNVENTORSL firie J44 ("our/ y .7 05)? .2: AZz'ne- TTORNE Y 9, 1941- K. w. CONNOR arm. ,2

VARIABLE PRESSURE HONING TOOL AND METHOD Filed Nov. 18, 1938 3 Sheets-Sheet 3 TORNE Y5.

Patented Dec. 9, 1941 VARIABLE PRESSURE HONING TOOL AND METHOD Kirke W. Connor, Detroit, and John E. Kline,

Grosse Pointe Farms, Mich., assignors to Micromatic Hone Corporation, Detroit, Mich., a corporation of Michigan Application November 18, 1938, Serial No. 241,104

13 Claims.

Our invention relates to honing devices and methods, and particularly to a honing device having control means for accurately regulating and controlling the pressure between the abrading tool and the surface to be machined during various phases in the machining cycle.

Heretoiore, it has been the practice to construct abrading tools with spring loading devices which produce a predetermined pressure on the abrading stones throughout the cycle of operation. In practicing our present invention, we provide a honing device having means for changing the pressure between the abrading members and the work member surfaces during the cycle of honing operation. Since the surface to be honed may be rough, very little area of surface engagement occurs between the stones and the projections on the surface. Initially, a light pressure is desirable to prevent the rapid wear of the stones which would occur when presented with high unit pressure against the rough surface. We have, therefore, provided means whereby initially. a light pressure is employed to grind the projections from the surface being operated on and thereafter, when material surface engagement obtains between the stones and the surface, the pressure is materially increased and the roughing operation completed under such increased pressure. For the finishing operation, the original light pressure or a pressure greater or less than such initial pressure may be employed for honing a desired finish on the surface. The employment of this lighter pressure permits the abrading particles to become dulled and yet not be dislodged as would be the case if high operating pressures were continued. The dulling of the abrasive permits it to produce a surface on the Work of a smoother character than the abrasive would produce if it remained sharp.

Various means may be provided for effecting the change in pressure. Sources of supply at variegated pressures may be provided which may be introduced selectively at various stages to produce the loading of the abrading stones. For the purpose of illustration, we have shown a pump for supplying a fluid to a line forming a rail system from which conductors may lead to a plurality of tools which are simultaneously operated. A relief valve is connected in the line to limit the rise in pressure to a predetermined amount. The valve is adjustable so that any desired maximum pressure may be obtained, which maximum pressure will be the pressure employed for the roughing operation. A second relief valve set to open providing the working pressure is also connected in the supply line, fluid to which is controlled preferably by a solenoid operated valve. When the latter valve is open, the supply line will have the fluid therein delivered at a pressure controlled by the relief valve of lower rating. This latter relief valve, determining the reduced pressure, may. function initially to provide the initial pressure to the abrading stones. A third relief valve, controlled preferably by a second solenoid operated, or other remotely actuated, valve, may additionally be employed to provide a still lower pressure which may be utilized either for the initial pressure or for the finishing pressure near the end of the abrading operation.

Various devices may be employed for controlling the operation of the solenoids to render the low pressure valves efiective. For the purpose of illustration, we have shown time switches which are set relative to each other and which control the entire cycle of honing operation and the cutting in and out of the relief valves to control the pressures during the various phases in the cycle or operation.

In a modified form of our invention, we have provided a valve which is automatically operated to increase the pressure on the abrading stones progressively and to progressively relieve such pressure during the cycle of operation. Cycle counters, time, relays, and the like may be employed for controlling the phases of building up and reducing the pressure of the system during the honing cycle. A valve is so constructed that initially the pressure is low and as the honing operation progresses the pressure progressively increases at a pre-set rate to a predetermined maximum during the roughing operation, after which the pressure diminishes to provide the dulling of the abrasive to produce the desired degree of surface finish on the work piece.

Accordingly, the main objects of our invention are: to provide a device and method for effecting an abrading operation under different pressures during different phases in the cycle of operation; to provide an initial pressure for the honing operation which is increased during the roughing cycle and diminished thereafter'during the finishing phase of the honing operation; to provide a device and means for progressively increasing the pressure during the honing operation and for thereafter progressively decreasing the pressure through the finishing phase of the honing cycle; to provide a plurality of relief valves and means for rendering the relief valves efiective and inefat a pressure materially below that of the valve fective during the honing cycle; to p viq lief valve which progressively increases and decreases the fluid pressure which is delivered to a honing tool; and, in general, to provide control means for the abrading element of a honing tool which varies the pressure during the various phases of the honing cycle, which is simple in construction and positive in operation.

Other objects and features of novel'- of our invention will be specifically pointed out or will become apparent when referring, for a better understanding of our invention, to the following description, taken in conjunction with the accompanying drawings, wherein:

Figure 1 is a diagrammatic view of a honing tool and the control therefor embodying features of one form of our invention;

Fig. 2 is a sectional view of a relief valve illustrated in Fig. 1;

Fig. 3 is an enlarged sectional view of the honing tool illustrated in Fig. 1, and the support therefo Fig. 4 is a sectional view of a valve controlling the direction of flow of the fluid to the honing tool;

Fig. 5 is a sectional view of the structure illustrated in Fig. 4, taken on the line 5-5 thereof Fig. 6 is a view of a valve similar to that illustrated in Fig. 4 having pressure regulating means thereon employed with the modified structure illustrated in Fig. '1;

Fig. 7 is a view of structure, similar to that ilof; and,

Fig. 8 is a sectional view of the pressure control valve illustrated in Fig. '1.

It has been pointed out hereinabove that the novel features of our invention embody the application of different pressures during the various phases of abrading occurring during an abrading cycle. In Fig. 1, we have illustrated a honing tool and control means therefor, which illustrates one form of structure and method which may practice our invention. One or more honing tools II are supported in the reciprocating head I2 for movement in rotation in a conventional manner. The tool is provided with a cylinder in which a piston is operated to apply pressure to the abrading stones for moving them radially of the tool axis. A fluid system supplies fluid under pressure to a valve I4 which may be shifted to direct the flow of fluid to the cylinders to one or the other side of the pistons therewithin. Suitable means, herein illustrated as a solenoid I5, is utilized for shifting the plunger of the valve I4.

Fluid is supplied from a reservoir I6 by a pump I1 to a supply line I8 which is connected to the A return conductor I9 returns the vlave I 4. fluid from the valve I4 to the reservoir I6. Directly connected in the line I8 is a'relief valve 2I which is adjustable to by-pass to the reservoir the fluid circulated by the pump I1 after the .pressure has reached a predetermined amount.

26 is open, the fluid in the supply line I8 is bypassed through the relief valve 23 and thereafter the pressure in the line I8 is that required to operate the latter relief valve.

A third relief valve 21 is herein illustrated as being connected in the line I8 in extension of the line 25 by a conduit 28 in which a solenoid operated valve 29 is disposed. When the valves 28 and 29 are both open, the relief valve 21, which is set to open at a pressure lower than the setting of the relief valves 23 and 2 I, will open and the pressure in the line I8 will be that required to operate the relief valve 21.

By adjusting the set screw 3| of the relief valves, as illustrated in Fig. 2, the tension on a spring 32 is adjusted to regulate the pressure on the valve 33. to the fluid delivered to the chamber 34 where the pressure will build up sufficiently to open the valve 33 to by-pass fluid to the conduit 35 into the reservoir I6. By selecting the proper position of the valves 26 and 29, any of the relief valves 2|, 23 and 21 may be made effective relative to the supply line I8 to thereby regulate the pressure of the fluid delivered through the line to the valve I4.

The flexible conductors I3 are connected to the conductors 36 and 31 which are joined by the couplings 38 and 39 respectively, to the upper and lower ends of the cylinders 4| of the honing tools II. A piston 42 is mounted in the cylinder 4| and is actuated in reciprocation by the fluid introduced in the cylinder on one or the other side of the piston. The piston 42 has an extension 43 thereon in engagement with a'plunger 44 which has, on the end thereof, conical shaped camming surfaces 45 which engage the projections on the abrading shoes 46 and which, when moved axially of the tool, control the radial position of the abrading elements 41. The plunger 44 carries a pin 48 which extends through slots 49 in the wall of the tool. The ends of the pin 48 project-into a collar 5I which is slidable in a threaded sleeve 52 limited by a projecting flange 53 to thereby control the degree of expansion permissible to the abrading stones 41. By adjusting the sleeve 52 the degree of radial movement of the abrading stones 41 is thereby regulated.

The valve I4, as illustrated in Figs. 4 and 5, embodies a housing 55 having an axially disposed opening 56 therein in which a plunger 51 is shiftable. Piston heads 58 and 59 carried by the plunger have a close fit with the walls of the opening 56 and control the passage of fluid from the delivery line I8 through the opening 6| and from either opening 62 and 63 to the flexible conductors I3 to the honing tool. When the fluid is passing through one of the openings 62 or 63 fluid is returned from the honing tool through the other opening and conducted to the reservoir from the opening 64 through the conductor I9.

Various means may be employed for operating the solenoid actuated valves I4, 25, and 29, such as counters, timing switches and the like, and

for the purpose of illustration, we have shown time switches 66, 61, and 68. The time switch 66 is set to shift and retain the valve I4 in a position to expand the abrading head of the tool and retain it expanded through the entire cycle of operation. The time control switch 61 is set to function after the switch 68 has energized the valve 26 to have the pressure in the delivery line I8 controlled by the pressure control valve 21. The time switch controls the valve 26 to have the pressure control-valve 23 effective when the valve 29 is closed.

When honing a cylinder for example, the honing tool is introduced thereinto and the time switches 66 and 68 are closed, the former of Regulation is thereby provided which shifts the plunger 51 on the valve II to introduce fluid through the conductors 31 into the top of the cylinder 4| to urge the plunger 33 downwardly. Since the time switch 58 was closed at the same time the valve 26 opens and the pressure in the line i8 is relieved by the pressure relief valve 23. In this manner, an initial low pressure is provided for expanding the abrading elements 61 into contact with the cylindrical surface of the work piece. In view of the rough walls within the cylinder, light pressure is desired during the initial machining phase of the honing cycle.

After a predetermined time of operation regulated by the time switch 68, the electric circuit to the solenoid of the valve 26 is opened, the valve 26 thereby becomes closed, rendering the relief valve 2| effective to control the pressure in the delivery line l8. Higher pressure is thereby delivered to the piston 42 of the honing tool and a material increase in pressure obtains between the surface of the abrading stones 4'! and the wall of the cylinders.

After a predetermined time, regulated by the setting of the time switches 61 and 68, both of the valves 28 and 29 are open to thereby have the pressure in the supply line l8 controlled by the pressure relief valve 21. The. pressure required to operate this valve may be materially less than that to operate the valve 23 so that the pressure employed for the finishing operation is thereby materially reduced.

In cases where the initial starting pressure and the finishing pressures are substantially the same, the pressure relief valve 23 may be employed for controlling both pressures and in such instance the valve 29 and pressure relief valve- 21 are omitted. After the finishing op-- eration, all of the switches 66, 61, and 68 are open, the valves 26 and 29 are closed and the plunger 51 of the valve It is reversed to have the pressure in the delivery line l8 introduced through the conduit 36 into the lower part of the cylinder 4| to move the piston 41 upwardly to thereby permit the abrading stones 4! to move radially inwardly under the bias of garter springs 69.

Referring to Figures 6, 7, and 8, we have illustrated a further method of controlling the pressure on the abrading stones during the honing operation. In this construction, a reservoir ll containing a fluid, such as oil, is connected with a pump 12 to deliver said fluid under pressure to a regulating valve 73 from which fluid passes from the conduit 14 to the valve M. A valve l5, similar to valve i4, is connected to a solenoid operated regulating valve 13 by a conduit I6. The solenoid of the valve 15 is controlled by a time switch 11 in a similar manner to that of the valve M by the time switch 66. The regulating valve 13 is similar to the pressure relief valve 2! of Fig. 2 with the exception that pressure from the chamber 34 is conducted through an orifice l8 beneath the piston head.

15 forming part of the valve 33. The piston head 19 has an orifice 8| therethrough which is materially less in cross-sectional area than the orifice l8 connecting the chamber 34 to the under side of the piston 19. The area above the piston is connected through a passageway 82 to the conductor 16 communicating the valve 15.

The pressure delivered to the chamber 3E initially raises the valve 33 against the tension of the spring 32 which thereby controls the pressure initially employed for expanding the &

abrading element. Fluid flows through the passage 18 to the underside of the piston head 19, and due to the fluid present on the opposite side of the piston a substantially balanced condition results. When the flow of fluid from the conduit 16 is less than that through the orifice 8! pressure will build up on the top side of the piston head 19 to thereby assist the spring 32 in endeavoring to hold the valve 33 closed. The increased pressure built up in the chamber 36 necessary to raise the valve 33 will be present in the delivery conduit 13. As the unit pressure in the chamber above piston head 19 increases, in the manner above described, the pressure in chamber 33 also increases by virtue of the bias of spring 32 reacting against a gradually balanced pressure area. Should, however, the unit pressure in the chamber above piston head 19 become exactly equal to the unit pressure in the chambers beneath piston head 19 and 34, the spring 32 would, in effect, be biased against an infinite pressure on a theoretically zero area causing the pressure of the fluid in conduit 14 to build up to the limit of pressure suppliable by the pump 12. To guard against such a circumstance, we have provided a bypass or relief valve 89 which is shown in detail construction in Figure 2. The spring of this valve is adjusted to the maximum unit pressure desired during the honing operation. When the flow of fluid from the conduit 16 is greater than the flow of fluid through the passageway 8|, the pressure is gradually relieved on the top side of the valve 19 and the pressure to operate the valve 33 likewise reduces, which gradually reduces the pressure in the delivery conduit 14 until the unit pressure operating upon the combined crosssectional areas of plunger 33 and the lower side of piston head l9 offsets the pre-set bias of the adjustable spring 32 in valve 13. The setting of this last mentioned spring determines the minimum pressure obtainable during the honing operation. With this arrangement the pressure on the piston 42 of the honing tool I I isinitially loaded with a predetermined low pressure which slowly increases during a predetermined time cycle of operation controlled by the time switch 17 and thereafter the pressure slowly reduces through the finishing operation.

This control of the pressure is regulated by the valve 15 which, as illustrated in Fig. 6, is provided with needle control valves 84 and 85. The stems 86 of the valves are adjustable so that a very fine bleeding of the liquid through the valves results. The valves are connected by conductors 81 to a line 88 which returns the fluid to the reservoir ll. When a plunger 59 of the valve 15 is shifted to one position, such as that illustrated, fluid from the conduit 16 passes through the needle valve 85, the rate of flow of fluid therethrough is less than that through the orifice 8i and pressure will build up on the top .of the valve 19 and in the delivery conduit 14. The pressure will continue to build up until the pressure reaches that for which the spring in valve 89 is adjusted. Thereafter, the time switch 7'! opens and de-energizes the solenoid of the valve 15 which permits the plunger 59 to shift to its opposite position. The fluid above the piston 19 will be conducted through the needle valve 84, the flow through which occurs at a greater rate than through the orifice 8| which thereby gradually reduces the pressure in the delivery conduit 14. This reduction of pressure will continue until the spring 32 in valve 13,

alone functions, or until the end of the cycle of operation when the timing switch 66 opens and operates the valve I. The valve l4 reverses the flow of fluid relative to the piston 42 and the plungers 44 are moved'upwardly to permit the abrading elements of the honing tool to be moved radially inwardly toward the axis of the tool. Low pressure will be present in the conduit 14 due to the fact that the needle valve 84 relieves the pressure on the top of the piston I9.

To start the cycle of honing operation, the time switches 66 and 61 are energized to close the circuit to the solenoid of the valves l4 and 15. The plunger 61 is moved to a position to supply fluid above the piston 42. The time switch 11 upon becoming energized moves the plunger 89 to the position illustrated in Fig. 6 to have the flow of fluid from above the piston 19 occur through the needle valve 85. The valve 85 bleeds fluid therethrough at a rate less than that which passes through the orifice 8|. The initial low pressure will urge the abrading elements against the wall to be machined during the beginning of the abrading operation. The pressure will automatically and gradually increase as the area of contact becomes greater between the gradually smoothing surface of the wall and the abrading elements. The maximum pressure is reached during the roughing operation, which pressure slowly decreases so that by the end of the roughing operation a pressure will be present satisfactorily low to produce the finishing operation. This cycle of reducing pressure occurs after the time switch 11 is de-energized to connect the valve 84 tohe conduit 16. After the finishing cycle has been completed, the time switch 66 opens the electric circuit to the solenoid of the valve M which is shifted to produce the retraction of the abrading elements.

It will thus be seen that we have employed the fluid delivered directly by a pump and have controlled the delivered pressure thereof by employing suitable relief valves. Through the operation of the valves, the pressure on the honing tools is maintained at various stages through different phases of the machining cycle. The pressure may be a predetermined amount or may gradually be built up and reduced during the honing operation and in repetitive phases if desired. The initial pressure may be such as to permit the grinding away of sharp machine marks left in the wall to be honed without materially damaging the surface of the abrading element. When area contact occurs between the surface and the stones, a materially increased pressure is employed for effecting the desired stock removal from the workpiece. Thereafter, a reduced pressure is utilized to produce the finish desired on the surface.

While we have described and illustrated several embodiments of our invention, it will be apparent to those skilled in the art that various changes, omissions, additions, and substitutions may be mad therein without departing from the spirit and scope of our invention, as set forth in the accompanying claims.

What We claimis:

1. The method of abrading which includes the steps of, initially abrading with a light pressure, thereafter abrading with a greater pressure, and finishing with said initial pressure.

2. The method of abrading in three stages which includes, initially abrading at low pressure to base metal, abrading at high pressure to remove base metal, and abrading at reduced pressure to finish the surface of the base metal which has been machined to size.

3. The method of abrading which includes the steps of, moving the abrading elements into contact with the surface to be machined, progressively increasing the pressure therebetween during the roughing operation, and near the end of the operation decreasing said pressure through the finishing phase of the honing cycle.

4. The method of abrading which includes the steps of, initially machining at a low pressure, thereafter increasing said pressure during the preliminary phase of the honing cycle, and decreasing said pressure for the operation during the finishing phase of said cycle.

5. In an abrading device, an abrading element, means for advancing said element into contact with a surface to be machined, means for initially applying a low pressure between said element and surface, means for thereafter applying higher pressure between said element and surface, means for applying a reduced pressure near the end of the honing operation, and means for controlling the duration of application of various pressures during the initial, roughing and finishing phases of the honing cycle.

6. In an abrading device, an abrading element, means for advancing said element into contact with a surface to be machined, fluid means for applying pressure to said abrading element, a first pressure control valve, a second pressure control valve for producing a higher pressure between said element and said surface and a valve for rendering said first control valve effective.

7. In an abrading device, an abrading element, means for advancing said element into contact with a surface to be machined, fluid means for applying pressure to said abrading element, a first pressure control valve, a second pressure control valve for producing a higher pressure between said element and said surface, a valve for rendering said first control valve effective, a third pressure control valve for providing a still different pressure to said abrading element, and a second valve for rendering such third pressure control valve effective.

8. In an abrading device, an abrading element, means for advancing said element into contact with a surface to be machined, fluid means for applying a pressure to said abrading element, a first pressure control valve, a second pressure control valve for providing a higher pressure between said element and said surface, a valve for rendering said first control valve effective, a third pressure control valve for providing a still different pressure to said element, a second valve for rendering such third pressure control valve effective, and means for controlling the application of said pressures during the various phases of operation during the honing cycle.

9. In an abrading device, an abrading element, means for advancing said element into engagement with a surface to be abraded, fluid means for applying a low initial unit pressure between said element and said surface and increasing said pressure to a predetermined maximum and thereafter decreasing said pressure to a predetermined minimum; and means for controlling the rates of increase and/or decrease of said pressures to maintain or retard, respectively, the abrading action of said elements.

10. The method of abrading which includes the steps of moving the abrading element into engagement and upon a-surface to be machined, moving said element relatively to said surface to effect an abrading action and subjecting said element to varying degrees of pressure, commensurate with the changing character of said surface, during the operation thereon, to maintain an efiectual penetration of the abrading particles of said element into said surface; and thereafter decreasing the applied pressure to reduce the pressure between said element and said surface to diminish the amount of said penetration to promote dulling of the abrasive particles and refinement of finish on said surface.

11. The method of abrading which includes the steps of moving the abrading element into contact and upon a surface to be machined, maintaining pressures between said element and said surface proportionate to their area of contact as the character of said surface changes, and subse-.

quently reducing said pressures to dull the abrasive particles in said element and thereby further increase the said area of contact during the final stage of operation.

12. In a hydraulic power transmission for operating a honing machine the combination with a translatable head and an expansible hone carried thereby, of a fiuid motor for effecting expansion and contraction of the hone, a pump for supplying pressure fluid to operate the .motor, and means for regulating the fluid pressure efiective on said motor to thereby control the expansive force exerted by the hone, said means including a valve for by-passing a portion of the fluid delivered by the pump, a piston for operating the valve and having one side freely communicating with the delivery side of 'the pump and its other side in restricted communication therewith, and a pilot relief valve for controlling the exhaust of fluid from said other side of the piston.

13. In a hydraulic power transmission for operating a honing machine the combination with a translatable head and an expansible hone carried thereby, of a fluid motor for effecting expansion and contraction of the hone, a pump for supplying pressure fluid to operate the motor, and means for regulating the fluid pressure effective on said motor to thereby control the expansive force exerted by. the hone, said means including a member. shiftable to control the quantity of fiuidvdelivered to the motor, a piston for operat-' ing said member and having one sidefreely communicating with the delivery side of the pump and its other side in restricted communication therewith, and a pilot relief valve for controlling the exhaust of fluid from said other side of the Piston.

W. CONNOR.

JOHN E. KLINE. 

